This invention generally relates to flow metering devices, and in particular relates to metering devices such as lubricators which supply a continuous flow of lubricating medium to mechanical structures, e.g. bearings or other moving parts of a machine.
Various devices have been heretofore provided for supplying a lubricating medium to the moving parts of a machine. Many machines employ a grease box or chamber into which grease is injected at periodic intervals by means of a grease gun or the like. In many applications it is not satisfactory to provide periodic lubrication and therefore continuous feed type lubricators have been developed. These lubricators employ a reservoir of lubricating medium such as oil with provision being made to feed the oil through a fitting into the machine. In certain of these lubricators the lubricant is propelled by means of a compressed gas, a resilient envelope, or a spring loaded piston. However, such prior art lubricators have a number of limitations and shortcomings. For example, it has been difficult to precisely establish a pre-determined lubricant flow rate and the prior art devices have not been capable of selectively varying the flow rate. Such prior art lubricators have also been relatively complicated in design, are expensive to manufacture and are relatively large and cumbersome. Moreover, lubricators have heretofore not been storable over a long period of time with the lubricant reservoir under pressure, nor have they been readily adaptable to being dismounted, stored for a period of time and then rapidly remounted and energized. Thus there is a requirement for a new and improved lubricator which will obviate the foregoing limitations and shortcomings of existing devices.